THE CHAMOIS. 93 



fracture on the slightest casualty. But to make them 

 strong, and at the same time retain their lightness, 

 a second set is thrown over the first, and the space 

 between is divided into cells, formed by the arched 

 girders of solid bone which uphold the roof and bind 

 the whole together. The system which Nature has 

 here adopted is exemplified in the cells in the upper 

 and lower part of the tube that forms the Britannia 

 Bridge. Just as these thin iron plates would sepa- 

 rately be unable to bear much, but placed above and 

 united to each other present an amount of strength 

 and firmness capable of resisting almost any opposing 

 force, so these fine thin bones of the chamois' head, 

 thus beautifully united by an arched cellular construc- 

 tion, become as firm as the rock on which the creature 

 stands, and are at the same time so light as not to 

 hinder any of its agile movements. The arched girders 

 which occupy the space between the upper and lower 

 surface rise, bridge-like, with a spiral twist, and here 

 and there a flying buttress will give additional strength 

 to the walls, or a lateral arch help to support the vault 

 above. 



The horn of the chamois is hollow up to a certain 

 height ; thence to the point it is a solid mass. This 

 hollow part of the horn however is fixed on, and 

 filled out with, a bony substance which grows with 

 and forms part of the skull itself. By a forcible twist 

 the two may be separated. When fighting the animal 

 lowers his horns under the throat of his opponent, or 

 turns his head sideways, that the sharp points may 



